The invention relates to a turbine part of a turbocompressor.
The invention also relates to a method of preventing carbon build-up in the turbine part of a turbocompressor.
In engine technology it is known to use turbocompressors for increasing engine power. A turbocompressor comprises a compressor part by means of which pressurized combustion air is fed to the engine. A turbocompressor further comprises a turbine part that runs the compressor. The exhaust gases from the engine are directed to the turbine that transforms the energy of the exhaust gases into compressor drive power. The exhaust gases from the engine are hot, whereby solutions have been provided for cooling the turbine unit. Cooling the turbine unit, however, decreases the temperature of the exhaust gases, which limits their utilization in a number of applications. Utilizing cooled exhaust gases in, for example, a waste-heat boiler is problematic, as the temperature of the steam produced or the heated water can not always be sufficiently increased. In addition, a large-scale cooling system makes the apparatus more complicated and increases its production costs. Because of this, uncooled turbocompressor devices are used in a number of applications.
It has, however, been observed that in some conditions carbon tends to build up in uncooled turbocompressors. The carbon build-up is common especially when heavy fuel oil is used as fuel. The temperature of the turbine surfaces in contact with the exhaust gas increases to a high level, whereby the carbon forming on the surfaces is especially hard. The carbon build-up is especially problematic in the area between the tips of the turbine blades and the flow channel surrounding them.
The properties of the carbon deposit vary according to the composition of the fuel; with vanadium- and sodium-containing heavy fuel oils the problem is especially considerable.
It is an object of the present invention to reduce the carbon build-up of the turbine part of a turbocompressor.